The present invention relates in general to a waste heat utilization system. More particularly, the present invention is concerned with an efficient system for utilizing power plant waste heat by attaining a stream of hot water preferably in the range of about 105.degree. F. to 125.degree. F.
Electrical power is typically generated using a boiler powered by either a fossil fuel or an atomic fuel and that generates steam for driving a steam turbine. Electricity is generated upon rotation of the steam turbine. The discharged steam from the turbine which may be at a temperature of say 100.degree. F. passes to a plant condenser where the steam is condensed prior to recirculation to the boiler. The condenser is a heat transfer device and typically water at an ambient temperature enters the condenser and is heated to an elevated temperature of say 90.degree. F. The water may be pumped through the condenser from a lake, for example, and may be discharged at the elevated temperature back into the lake. Systems have been devised previously wherein the waste heat is elevated in temperature even by using a secondary heating source to, for example, heat a building. Generally, systems of this type have been limited to use with only a single power plant. A paper was published in the "transactions of the ASME" (paper No. 75-PWR-12, published in July 1976). Ileri, Reistat, & Schmisseur discussed the use of waste heat from power plants. They discussed in general two limiting cases including a high temperature scheme using hot water derived directly from the plant extraction steam system and a low temperature scheme using the plant circulating water at the temperature at which it comes from the plant which may be on the order of typically 90.degree. F. The high temperature scheme has certain disadvantages in that it requires extensive plant modifications and also requires a special high temperature conduit. On the other hand the low temperature scheme is inadequate because of the relatively low unstable temperature at which the water is delivered. Also, neither of the schemes proposed in that paper provide for using more than one power plant as a heat source.
Accordingly, one object of the present invention is to provide a system for utilizing power plant waste heat in obtaining a stream of hot water preferably in the range of 105.degree. F. to 125.degree. F.
Another object of the present invention is to provide a waste heat utilization system which is efficient in operation and which permits the combining of the discharges of several plants in the total system concept.
A further object of the present invention is to provide a waste heat utilization system that comprises an improved condenser system and associated control for providing either single pressure, single pass condenser operation or multi-pressure, multi-pass condenser operation.
Still a further object of the present invention is to provide a waste heat utilization system in accordance with the preceding object and which includes temperature control means for maintaining the stream of hot water at a predetermined temperature and preferably maintaining the same temperature for the discharges from each power plant.
Another object of the present invention is to provide a special pressure control provided at all plants to compensate for variations in water flow occasioned by changes in electric generation.